\begin{aligned} linear: & K (x^{'}, x) = ⟨ x^{'}, x ⟩ \\ polynomial: & K (x^{'}, x) = (c ⟨ x^{'}, x ⟩)^{d} \\ rbf: & K (x^{'}, x) = \exp (- c ‖ x^{'} - x ‖) \end{aligned}